Process of treating hydrocarbon oil



Filed June 16, 1933 3 Sheets-Sheet l FERC/VAL C. /fE/THJR n, l l l l 1 l |l|| x l I 1 |||||I||||uo` ATTORNEY- Filed June,l6, 1933 3 Sheets-Sheet 2 INVENTOR- PERCIVAL C'. /fE/THJ/e MM# W ATTORNEY- NOV 23, 1937. P. c. KErrH. JR

PROCESS OF TREATING HYDROCARBON OIL Filed June 16, 1953 3 Sheets-Sheet 3 Patented Nov. 23, 1937 UNITED STATES PATENT OFFICE PROCESS F TREATING HYDROCARBON OIL Application June 1s, 193s, serial No. 676,127'

11 claims. (c1. 19e-4s) l This invention relates to processes and apparatus for the production of gasoline from raw crude oil. v

In the treatment of raw crude oil to produce gasoline it has heretofore been generally customary to form from the crude oil either by distillation alone or distillation coupled with mild cracking, a distillate stock suitable .for charging to a major cracking operation, this stock being subsequently treated under cracking conditions of heat and pressure to produce the desired gasoline product. In carrying on 'a process of this character it has usually been customary to separate various oil fractions and to regard them somewhat in the nature of by-products which are more suitably treated in independent operations, or even classified as marketable products without further processing. For example, a well known,

j method is to separate from raw .crude oil a gas oil charging stock which is thereaftersubjected to cracking in a separate operation, complete in itself, to produce gasoline. This gasoline in many cases has been of such character as to require further processing, such as reformation and stabilization, to form a final gasoline product complying with the desired specifications. Likewise in many instances it has been found desirable, prior to the separation of the gas oil, to top the raw crude and subject the resulting unvaporized portion to a light crackingoperation of a viscosity breaking nature whereby 'the content of gas oil may be increased. Various additional steps in the processing of crude oil'for the production of gasolinehave also been undertaken independently. l

It is an object of my invention to provide a unitary process for the treatment of raw crudefoil whereby all the operations necessary to produce a maximum amount of gasoline'of nal desired end point and characteristics may be carried out at the same time in a series of interlocking steps s0 related one to the other that a minimum amount of heat and attention are neceary, and high eiiiciency results. By combining all of thevarious steps Which have heretofore been performed individually or in some incomplete combination one with the other, it i's possible to utilize more advantageously heat which might otherwise be wasted, and also keep at a low figure the amount of -labor and supervision necessary in the operation of a system to carry out the process.

More specifically it is an object of my invention to combine in a single unitary process forthe treatment of raw crude oil, the steps of topping the raw crude, viscosity breaking the topped crude, cracking a clean condensate stock, reforming any necessary portion of the gasoline produced to raise its anti-knock value to the desired point, and stabilizing gasoline distillate resulting from these operations to give a final desired product of the proper end point and vapor pressure.

The above mentioned and further objects and advantages of my invention, and the manner of attaining them will be made clear'in the following description taken in conjunction with the accompanying drawings.

In the drawings Figures 1 and 1a represent together a. .schematic view in side elevation and partly in section of a combination cracking unit constructed in accordance with my invention and Fig. 2 is a simplied ow diagram thereof.

Referring more particularly to the drawings, reference numeral I indicates a crude flash tower; 2 an evaporator; 3 a viscosity breaking furnace; 4 a vapor phase furnace; 5 a soaking drum; 6 a fractionator; 'I a primary gas separator and 8 a stabilizer tower.

Charging oil, f or example 37 A. P. I. Mid-Continent crude, is introduced through the charging line 9 and is forwarded by action of the pump I0 through heat exchangers II, I2, I3, and I4,- whereby it is raised to a temperature sufficient to cause the vaporization of light naphtha, for example 450 F. more or less. The amount of light naphtha so vaporized will vary according to the character of the crude and may represent about 10% to 30% of the initial charging stock and the gravity of this naphtha may be in the neighborhood of 67 to 71 A. P. I., e. g. 70 A. P. I. The raw crude thus preheated is then introduced into primary flash drum I5 of the crude flash tower I wherein vapors are released. This primary sec- --tion is provided with fractionating devices such as bubble trays I6. Light virgin naphtha is withdrawn through vapor line I'I and after passing through one element of the heat exchanger I I travels through final condenser I8 into storage drum I9. drawn from the drum I8 and introduced through `'pipe 20 having valve I2I, into the top of the primary ilash drum-'I5 as a. refluxing medium or cooling oil, by actionof pump 2l. The unvaporized portions of the raw crude charging oilwhich may be at a temperature of from 410440 F. for

example, are passed from drum I5 into secondary ash drum 22 through pipe 23, having liquid level control valve 23', which serves to maintain a de- 'sired liquid level in drum I5.

In the secondary ash drum further vaporization of the introduced liquid takes place, this Light virgin naphtha may be Withu v being mainly caused by contact with hot vapors by heat of the vapors from the tar flasher pass, upwardly through bubble trays or similar devices 28 and 29, cooling oil or reuxing medium being supplied through pipe lines 30 and 3|, valves 33 and 34 serving to regulate the amount of reflux so supplied. The refluxing medium supplied through pipe line 3| maybe heavy naphthar withdrawn from accumulator drum '86 by action of pump 32, while the liquid introduced through pipe line 30 is preferably a light gas'oil from a receiver 38, which is forced by pump through conduit |22 into pipe .line 30. A trap' out tray 35, which is positioned at an'intermediate point in secondary flash drum 21V-"just above the point of entrance of the reflux pipe 36, serves to collect clean light gas "oilv which is' drawn off through line 31 and directed into receiver 38. The temperature of the liquid in the tray may be about 450 to 550 F.,'for example, 475 F. and the amount of gas oil so withdrawn may represent about 1,2% of the initial charge, the gravity of the gas oil beingf'for example, about 36 A. P. I. Overhead vapors tare withdrawnthrough pipe 86 and are introduced into the accumulator drum after passing through lcondenser coil |80. The vapors so withdrawn consist primarily of heavy naphtha ofj'for example, about 46 A. P. I. gravity, and may represent',f'for example, 19% of the initial charge. The heavy unvaporiaed liquid remaining in the bottom of the secondary flash drum and consisting of reduced crude including heavy gas oil and other unvaporizedz'portions of the raw crude`charging stock, and'f'condensed portions of the vapors from the fuel oil flash drum having a; gravity of,'"f0r example, about 22 A. P. I., iswithdrawn through drawoff line 39 and heat exchanger ,26, and is forcedby action of pump 4| through pipe 40 and heatfexchanger 42 into'an intermediate point in the' evaporator tower 2. The temperature .of the reduced crude is increased by heat derived from the'heat exchangers 26 and -42', prior to itsv introduction into the evaporator. AFor example, the temperature of the heavy oil may be about 535 F.' the base of the second flash tower S50-670 F'. after passing through heat` exchangerI y2|i and '1D0-715 F. after passing through heat exchanger 42. The temperature increase resulting from passing the heavy oil throughrthese exchangers""might be greater or less than that mentioned, depending on the amount and temperature of the hot productsavailable for heat exchange. This `heavy oil enters the evaporator above baille plates or other fractionating devices 43 and flows downwardly over these plates against the upwardly rising vapors of the evaporator., onto trap out tray 44. The liquid collected on trap out tray 44, which may be stripped of light fractionsby water introduced through line 44', flows by gravity through pipe 45 into accumulator drum 46, which has a vent line |23 for conducting any vapors back to the evaporator 2.l rlfhe quantity of liquid ,so withdrawn may be, for example, about.39% reduced crude from the charge and 61% recycle stock, although these percentages are subject to variation depending on the stock being treated, and the operating conditions. The entire amount of withdrawn liquid may be for example, approximately to 150% although this percentage would be subject to wide variations, depending on the charging stock used, and operating conditions generally, for example, from less than 100% to more than 200% with respect to the initial charging stock. The gravity of this composite stock charged to the viscosity breaking furnace may be about 22 A. P. I. Oil may be passed from pipe A4|) directly to this accumulator drum, through pipe |25 havingvalve |26 whenever desired, for control'purposes. Liquid collected in the accumulator drum 46 is withdrawn through pipe 41 and forced by action of pump 48 through the heating coils of the viscosity breaking furnace 3. The temperature of the product entering the furnace may be approximately the same as that of the liquid when drawn off `from the trap out tray 44, e. g. 7,50- 800 F. Upon entering the furnace the charge oil travels in two parallel streams, each controlled by a manually operable valve or an automatic flow regulator 41', first through Shield coils in the portion of the convection section of indicated' by reference numeral 49, next upwardly through radiant coils in the combustionchamber'50 of the furnace andfinally lthrough a soaking coil in a cooler portion 5| of the convection section of lthe furnace, concurrent with the furnac'e'gases, the final ltemperature attained bythe oil being suflicient to promote a moderate amount of cracking; e. g. suflicient t0 convert the oil into 8 or 10% gasoline and 22- 24% charging stock for the vapor phase furnace. This temperature may be from S40-880 F.,'about 850 F. being generally preferable. Reference numeral |65 indicates the bridge wall of the furnace. l

'I'he hot oil after leaving furnace 3 flows through the conduit 52 into thelower portion of evaporator 2, preferably without any substantial 'reduction' of pressure. The evaporator is preferably operated at `a moderatepressure, for example -215 pounds per 'square inch'. y'The heating of the charge in theviscosity breaker furnace causes a moderate amount of cracking and therefore theproducts introduced into the base of the evaporator tower contain lighter fractions which vaporize, the vapors passing upwardly through' the evaporator'tower. The `'upward passage of the vapors is obstructed by baille plates 53 Vlocated below the trap out tray 44 and bubble trays or other fractionating devices 54 located above the trap out tray, as well as by the baille plates 43 already mentioned. A relatively light clean stock is introduced both above the baille plates 53 through pipe 55, and above the bubble trays 54 through pipe 56, as a refluxing medium, in order to promote fractionation of the rising vapors. The liquid introduced may advantageously be light gas oil, delivered through a Acommon supply line 51 into which oil' withdrawn from the gas oil receiver drum 3B is forced action of baille plates 62 and bubble trays 63. Pipe line 64 is provided for introducing a light clean refluxing medium, such as the light gas oil already mentioned, into the fractionator 6 at an intermediate point'above the bale plates 62. This pipe line may have an adjustable cooling device 65 whereby the temperature of the introduced oil may be varied, valve 66 being furnished to regulate the amount of refluxing medium supplied. Reiiuxing liquid for the bubble trays in the top of the fractionator is provided by withdrawing liquid from a tray near the top of the tower, cooling this liquid by indirect heat exchange with the raw crude oil in heat exchanger I3 andreturning the cooled liquid to the top of the tower. Pipe line 61, which vcirculates the refiuxing medium,-is provided with a pump 68, a control valve |68 and an auxiliary cooler 69 having control valve |68 that serves additionally to cool the circulated liquid and to control the end point of the gasoline. An automatic thermostatic device 69' serves ,to maintain constant the endpoint of the gasoline derived from the tower 6, by increasing the amount of liquid passing through cooler 69, upon a rise in the temperature of the overhead vapors in the tower and vice versa. This fractionator is preferablyI operated under substantially the same pressure as that of the evaporator tower 2.

Gasoline vapors remaining uncondensedv by the fractionating action of the tower are removed from the top thereof through vapor line 10 and passed through condenser 1| `into the primary gas separator 1. The temperature of the vapors leaving the tower may be, for example, approximately 435 F. and that of the condensed liquid in the gas separator F. The lower part of the fractionator tower 6 acts as a liquid reservoir while above the liquid level and below the vapor' inlet to thev tower are bubble trays 12 and an accumulator pan 13. The accumulator pan collects part ofthe light .gas oil reflux condensate formed during the fractionation of the vapors and this condensate is conducted in desired quantities either directly through drawoff line 14 and heat exchanger I4 into the light gas oil accumulator 38, or through pipe line 15 and heat exchanger 16 into the accumulator drum 38, or both. The condensate so drawn oif may have a gravity of about 25 A. P. I., suiicient being removed to maintain the level in drum 38. Any excess of condensate not withdrawn from thepan 13 overflows into the lower part of the fractionator. Valves |28 and 11 provide the necessary control for regulating the iiow of the condensate. Water may be introduced into the frac- Y .60' the lower part of the fractionator may be about 700 F. and that of the liquid in the accumulator 38, 500 F. thereabouts. Additional oil may be introduced into accumulator 38 from an external source through line |56, whenever necessary.

A reducing valve or orice 18 serves to reduce the pressure on the condensate prior to its introduction into the drum 38, after passingthrough heat exchanger Ul, and a similar reducing valve or oriiice 19 performs a similar function for the condensate subsequent 'to its passage through heat exchanger 16. 1

sure slightly less than that of the fractionator tower, for example 175 pounds per square inch when the fractionator pressure is 200 pounds per square inch. The gasoline distillate mixture contained in the gas separator 1 .is roughly freed from incondensable gases, which pass off through gas line 83 while the remaining distillate is withf drawnA from the primary lgas separator and forced by pump 84 through pipe line 85 and heat ex-A v changer 86 into the stabilizer tower. The distillate enters at an intermediate point. in the tower above a plurality of bubble trays 81 and heat exchanger 16 by pump 9|, the heated liq'A uid being returned' to the stabilizer below the accumulator pan'89. The heat. exchanger 16 acts as a reboiler for the distillate in the base of the stabilizer column. Stabilized gasoline of the desired end point,` automatically regulated by adjustment of valves |68 and |68', for example is withdrawn from the bottom of the stabilizer through pipe line 92, heat exchanger 85, and auxiliary cooler 94, in the form of a finished product. The end point of this gasoline is determined by the cooling effect of the liquid introduced through line 61 into the top of the fractionator. The gasoline "produced may be clay treated in the vapor phase, or liquid phase, or acid treated, either before or after stabilization,'in the usual manner, if desired. This cooling effect is controlled automatically by action of thermostatic device 69' in the top of the tower, which regulates the amount of returned liquid passing through cooling coil 69, by operation of valves |68 and |68'. The valves |68 and |68' may of course be manually adjusted if desired. The heat transferred by the distillate withdrawn through pipe 92, through the agency .of heat exchanger 86, raises the temperature of the distillate'introduced into the stabilizer column.. The temperature of the distillate entering the stabilizer may be approximately 320 F. 1 Vapors and incondensable gases are withdrawn from the top of the stabilizer column through pipe and cooler 96 and resulting condensate is introduced into reux drum 91. The vapors leaving the ytower may have a temperature of 135 F., for example, while the liquid in the reflux drum may be held at a temperature of, for example,

F. Liquid may be withdrawn from the bottom of the drum 91 and forced through pipe line v98 into the top of the stabilizer column as a reiiuxingvmedium. The pump 99 supplies the necessary pressure and the amount of liquid so pumped back may be controlled by adjustable valve |00. Stabilizer gas is withdrawn from the top of the drum 91 through pipe line |0|.

Rei-lux condensate collecting in the base of 'fractionator 6, being a clean stock having a gravity of about 25 A. P. I. and a color. of about 3 N. P. A., for example, aswell as a relatively low carbon content, of preferably not over .1% by the Conradson test, is withdrawn through pipe line |02 and forced by action of pump |03, through vapor phase furnace 4 and the connected soaking drum 5, wherein the condensate is subjected to cracking in the vapor phase, preferably at a temperature of less than '1000" F. and more than 850 F., most desirably 900-950 F., and a pressure of 100 to 400 pounds per square inch, most desirably 195 to 225 pounds per square inch. The cracking to gasoline per'pass is preferably in the neighborhood of 15 to 20%, the greatest part of this conversion being effected at temperatures above 850 F. These moderate cracking conditions have been found to Iproduce a relatively high anti-knock gasoline without the simultaneous formation of excessively large amounts of fixed gas or heavy products such as tar or coke. The anti-knock rating of the gasoline produced can be increased, if desired, lby.

increasing the temperature, or the percentage of cracking to gasoline per pass. The vapor phase charge may be, for example, in the range of 160 to 200% with respect to the quantity of initial charging stock for the system. A considerable proportion of the products from the vapor phase coil may be recovered by condensation and recycled, this amounting for example to about '70% of the total charge to the coil. The stock subjected to vapor phase cracking is preferably at least as clean as stated hereinbefore since less clean stocks tend to form objectionable carbon deposits in the cracking apparatus.

The cracked products leave the furnace and flow into soaking drum 5 through conduit |04, preferably without any substantial reduction in pressure.- The soaking drum is preferably operated at substantially the same pressure as that of the evaporator tower and fractionation tower, e. g. 195 to 225 pounds per square inch. In the soaking drum additionalv cracking takes place, the soaked vapors passing overhead through pipeline |05 having pressure control valve |05' and flowing into the lower Dart of the evaporator tower adjacent the point of entrance of the cracked stock from' the viscosity breaking furnace, and below the level of bailie plates 53. The temperature of the vapors leaving the soaking drum 5 is somewhat less than that of those entering the drum, for example about 835 F., when the inlet temperature is about 935 F. A light, clean, entirely vaporizable liquid, such as light gas oil, is introduced into the top of the soaking drum adjacent the vapor outlet in order to prevent coking of the vapor line. This may be done through pipe line |06 which connects with pipe 51 leading to the light gas oil storage drum 38. Pipe line 51 has heat exchanger I2 and line |06 has exchanger 93, vas well as auxiliary cooler |01 therein whereby the temperature of any gas oil introduced into the soaking drum is reduced to a suitable value. Cross-over line |06 having valve |01 is furnished for Vintroducing cool oil directly into the vapor line when additional cooling is desired..l Coil 93. connected by pipe 93 with pipe line |96. serves to coolthe oil in the soaking drum adjacent to the point of connection of the emergency circulating and drawolf line |29, thereby inhibiting coke deposition at this outlet. 'I'he line |29, which is used largely as a circulating line during the bring-up period is provided with valve |29. The amount of oil passing through the cooling coil may be regulated by means of valves |30. |3I'. and |32.

The chargingv stock passes through vapor phase furnace 4 in'two parallel streams which are symmetrically arranged. Each stream passes first through a convection coil located in the cooler of two tubes in 'parallely located in combustion chambers |09 of the furnace and `finally down:

if wardly concurrent withv the furnace gases,

through a. soaking coil consisting of three tubes in parallel and located in the hotter portion H0 of the convection section of the furnace. Reference numerals |66 and |61 indicate the furnace bridge walls. The convection coil raises the temperature of the oil relatively slowly, while the radiant coil increases the temperature more quickly to a higher value .to promote cracking, and the soaking coil holds the temperature substantially constant at that value. Upon leaving the furnace the two streams unite for introduction into the soaking drum. The inlet pressure of the vapor phase coils may be, for example, about 420 pounds per square inch and the outlet pressure just sucient to force the cracked products into the evaporator 2, e. g. 200 pounds The amount of cracking accomplished in theA coils of the vapor phase furnace may be, for ex-A ample, l3 to 15% per pass, while due to the additional cracking accomplished in the soaking drum.5, thetotal amount of vapor phase cracking per pass may be somewhat higher, for ex.

ample 18 to 19%.

A light tar residue having a gravity of, for example, about 16 A. P. I., is withdrawn from the bottom of evaporator 2, through pipe line having a reducing valve |49, and introduced into tar flasher drum 24 at an intermediate point in a series of baffle plates H2. The temperature of'the oil in the flash drum is somewhat lower than in the bottom of the evaporator, e. g. '725 to '175 F. This drum is held under reduced pressure, preferably substantially atmospheric, and the vapors evolved therein pass upwardly through vapor line 25 and heat exchanger 26 into the lower part of secondary flash drum 22, in the manner already discussed liereinbefore. A light clean oil reflux such as light gas oil may be introduced above the bale plates ||2 through duced into line |55 to reduce the viscosity of the fuel oil. Line is provided so that hot vapors from the evaporator may be introduced into vdrum. 24 whenever necessary to maintain` thedesired temperature. The point of connection of to the evaporator is higher than that of so that vapors may be withdrawn rather than liquid oil. l

The heavy naphtha'accumulated in drum 90 is v stripped of its light products of a gasoline nature by aid of fractionator or stripper tower |3| to which vapors from the drum 80 pass by way of line |32. The fractionated vapors of a gasoline nature pass overhead through vapor line |33, are condensed in coil |34 and stored in reservoir |35, while reflux condensate is' returned from the fractionator to the drinn 80 by conduit |35.l A drawo' line |31, pump |38 and pipe |39 having control valve |4| are furnished for returning gasoline from the reservoir |35 to fractionator ll as a reuxing medium, and a conduit |40 having control valves |42 serves to conduct gasoline from.

pump |38 to pipe line 64 as a reuxing medium in bubble tower 6, whenever desired. -Light naphtha for example, about 46 A. P. I., is removed from the accumulator drum 80 and forced by action' of pump 32 through pipe line 4 leading to reform-` ing coil II5 positioned in vapor phase furnace 4.

I' The temperature of the naphtha entering the reforming coil may be 20D-300 F. and its temperature upon leaving the coil after passage through the furnace may be from" 950 to 1050 F., preferably about 1000 F., whereby a conversion to about 57% of high anti-knock gasoline, 18% gas oil, 5% fuel oil and 19% gas results. The converted material travels through pipe l|6 which connects Withthe evaporator 2 at substantially the same level as pipe 52.

In normal operation it is preferable that the heavy naphthato be reformed be that .separated from the crude charge, that is, perhaps 15% tol 20% of the crude charge, this being in amount about 10% t'o 15%, for example, with respect to -the quantity of oil charged to the viscosity breaking operation, but in certain cases it may be desirable to increase this amount by including with it vsome or all of the gasoline stripped from the,

charge, or even to add naphtha from an external sourcethrough pipe |I4.' having pump 32'; The

inclusion of some of the gasoline would increase the anti-knock value of the nal product produced by the system but would-also tend to increase gas losses and otherwise lower the operating efficiency. When a lower anti-knock final product is desired A naphtha introduced into the evaporator is small with respect to the amount of stock supplied nace the naphtha to be reformed rst flows upwardly through a coilsection II'I located in the 'convection portion vof the furnace 4, then through a. coil section ||8 synmietrically arranged in the .radiant portions of the furnace. A cooling liquid such as light gas oil is introduced into the transfer line I IBadjacent its point of connection with the furnace in order to prevent'coke formation in the line. Pipe line v'|52,having control valve |53, interconnects gas oil line 51 with line I I6 for this purpose. The outlet temperatures of. the reformed naphtha may be maintained constant by valve I I6' automatically regulated by thermostatic controller I I'l coupled to the transfer line IIB. The pressure on the naphtha entering the reforming coil may be about 800 pounds per square inch and ,its pressure on leaving'the coil may beI 'about 600 pounds per square inch, for example,

the pressure then being reduced, by passage through valve 206, to that existing in the evaporator.

A pipe line |43 having a pump |144 and control valve |45 serves-to circulate evaporator bottoms through heat exchanger 42, thereby heating the topped crude passing through line 40 and supply-l f ing cooling tothe bottom of the evaporator sumcient to maintain the temperature thereof .below a connect with the pipe at several points along the length thereof, indicated by numerals 400,

40|, 402, and 403, so that the cooled oil is mixed with the hot vapors from thev soaking drum 5, or it may be connected directly into the bottom of the evaporator. The drop of temperature of the h ot ing furnace.-

vapors from soaking vdrum E by introduction of cooled' oil from line |43 into line I 05, may be about 15 F. for example- By introducing cooling oil at a plurality of spaced points along vapor line |05 local deposition of coke, which tendsv to occur Where a single pointof introduction is used, is

avoided. By putting the cooling or fluxing stock in at a plurality of points complete drying out of the coolingstock in the line is prevented. Connection I4' provides a path whereby cracked products from the bottom of soaking drum 5 may be passeddirectly from line |29 into the light tar line I I I leading to the flash drum 24, under control of valve I 48.- A similar connection |50- having control vaF/'e |5I `issupplied so that desired amounts of cracked products may be introduced directly into .the base Vof the fractionator. These lines are mainly used in starting up.

" The vapor phase furnace hastwo separately and independently fired combustion chambers or radiant sections, and a common 'convection section. Each one of the symmetrical vapor phase coils located in portions |08 and |09 of the furnace, has two'tubes in parallel, and each coil in the soaking section I I0 three tubes in parallel,

`as already mentioned. In order to insure an equal amount of heating of the oil passed through eachvapor phasepath a separate flow controller |I9. is,pi'ovided foreach path and in addition a temperature controller |20 preferably located at the end of the radiant coil section just prior to its connection with the soaking section, is provided for each path likewise. T he flow controllers maintain'ccnstant the flow of oil through each ofthe parallel paths, while the temperature controllers regulate lthe amount of fuel suppliedI to each combustion chamber in such manner as to insure the proper constant outlet temperature for each path. The temperature of the reformed naphtha is independently regulated as described hereinbefore, if desired.

Valves 200, 20|, and 202 are provided for controlling the iiow through their associated lines; the valve 202 may be of the pressure reducing type if desired. Valvesll serves as the primary control of the supply of oil to the viscosity break- Valves 203 and' 204 are provided to control the i'low through their associated lines while the necessary control for the vapor phase cracking operation is effected primarily by valves IIIl. Valve 204 may be of the pressure reducing type if desired, while valves 205 and 206 serve to control the reforming operation, -any desired pressure regulation being effected by valve 206.

I prefer to usethe temperatures and'pressures already mentioned, for the viscosity breaking, cracking and reforming operations, particularly for producing gasoline of approximately 70 octane number, from a charging stock such as 37 A. P. I. Mid-Continent crude, butsomewhat higher or lower temperatures and pressures may be used, the exact conditions being determined in each case by the character of the charging stock and the specifications of the nal desired products. Furthermore, vvhenevendesiretl,l the pressures of the several cracking operations may be adjusted independently to selected values to produce known effects on the individual stocks being treated. And the octane number and other characteristics of the final desired product -may be regulated by varying the cracking temperature the cracking per pass of the individual stocks, or the total amount of cracking of these stocks. The parallel flow furnaces disclosed may be replaced by conventional single path furnaces, if desired.

While I have described a particular embodiment of my invention-for the purposes of illustration it should be understood that various modifications and adaptations thereof 'may be made within the spirit of the invention as set forth in the appended claims.

I claim:

1. The process of treating hydrocarbon oil which comprises introducing relatively heavy oil comprising residual constituents and lighter constituents into a stripping zone wherein said oil is separated into vapors and a liquid residue, removing said residue from said stripping zone and passing residue so removed through a first cracking zone wherein it is raised to a cracking temperature and subjected to conversion while passing inv a stream of restricted cross-sectional area through a heating zone, introducing the resulting cracked products into an evaporating zone wherein vapors separate from liquid residue, fractionating vapors evolved from said oil in said.

stripping zone to form a condensate suitable for use as clean cracking stock, passing condensate so derived through a second cracking zonel wherein it is raised to a cracking temperature :and subjected to conversion while passing ina stream ofrcstricted' cross-sectional area'through a heat; ing zone, introducing the resulting cracked products into said evaporating zone to be in admixture thereinwith the products from said firstmentioned cacking zone, removing liquid residue from said evaporating zone, reducing the pressure on the residue so removed to cause partial vaporization thereof, passing resulting vapors up wardly through said stripping zone to aid in heating and distilling thev said` heavy oil introduced thereinto, while preventing the mixture with the stock passing through said first and second cracking zones of undistilled portions of said residue last-mentioned, and fractionating vapors separated in said evaporating zone to form a final desired light product'.

' 2. A process in accordance with claim 1 wherein the condensate'removed from said stripping zone and passed through said second cracking zone includes gas oil fractions and wherein a lighter condensate comprising gasoline constituents is removed from said stripping zone, passed through a third zone in a stream of restricted cross-sectional area wherein it is raised 'to a relatively high cracking temperature suilicient to cause vthe reformationthereof and subjected to conversion, and the resulting reformed products are introduced into said evaporating zone.

3. The process of treating hydrocarbon oil which comprises introducing relatively heavy oil comprising residual constituents and lighter constituents into a stripping zone wherein said oil is separated into vapors and a liquid residue, removing said vresidue from said stripping zone and passing -residue so removed through a rst cracking zone wherein it is raised to a cracking temperature and subjected to conversion ,while passing in a stream of restricted cross-sectional area. through a heating zone, introducing the resulting cracked products into an evaporating zone wherein vapors separate from liquid residue, fractionating vapors evolved from said oil in said stripping zone to form a condensate suitable for use as clean cracking stock, passing condensate so derived through a second cracking zone wherein it is raised to a cracking temperature while passing in a stream of restricted crosssectional area through a heating zone,'introduc ing the resulting cracked products into said evap-` ling said reflux condensate with the oil passing through said second cracking zone, withdrawing from `said stripping zone a second and lighter condensate comprising gasoline constituents, passing condensate so withdrawn through a third zone wherein it is raised to a relatively high cracking temperature sufficient to cause the formation of relatively high anti-knock gasoline constituents, and introducing the resulting reformed products into said evaporating zone.

4. The process of treating hydrocarbon oil which comprises passing f resh relatively heavy charging stock into a stripping zone wherein partial vaporization thereof occurs, removing the residual portion of said charging stock and introducing it into an upper level in an evaporating zone wherein hot vapors pass upwardly counter-current to the residual portion sointroduced, causing partial vaporizationv thereof, removing from an intermediate level in said evaporating zone below said upper level unvaporized portions of said residual portion in mixture with condensed fractions of the rising vapors, passing the resulting mixture through a cracking zone wherein it is raised to a cracking temperature and subjected to conversion while traveling in a stream of restricted cross-sectional area through a, heating zone, introducing the resulting cracked products into a still lower level in said evaporating zone wherein vapors separate from liquid residue, said vapors passing upwardly through said evaporating zone and constituting a source of said hot vapors rstmentioned, preventing the passage upwardly through said evaporating zone to a point above said intermediate level, of heavy entrained constituents by washing the vapors below said intermediate level with a downwardly owing stream of refluxing liquid, removing said liquid residue from said evaporating zone and directing it into a flashing zone wherein further sep- I aration of vapors from residue takes place and passing vapors thus separated into said stripping zone.

5. The process of treating hydrocarbon oil which comprises introducing fresh relatively heavy charging stock into Aa stripping zone wherein partial vaporization thereof occurs, removing the residual portion of said charging stock and introducing it into a. rst fractionating zone wherein hot vapors pass upwardly counter-current to the residual portion so introduced, causing partial vaporization thereof, removing froxn a lower portion of said rst fractionating zone unvaporizedy portions of said residual portion in mixture with condensed fractions of said hot vapo-rs, passing the resulting mixture through a first cracking zone wherein it is raised toa cracking temperature and'subjected to conversion while traveling in a stream of restricted cross-sectional area through a heating zone, introducing resulting cracked products into an evaporating zone wherein vapors separate from liquid residue, passing resulting vapors into said rst fractionating zone as a source of said hot vapo-rs first-mentioned, passing uncondensed vapors from said rst fractionating zone into a second fractionating zone wherein separation thereof into fractionated vapors of the desired boiling characteristics and a reflux condensate occurs, condensing said fractionated vapors to form a desired product, removing said reflux condensate and passing it through a second cracking zone wherein it is raised to a cracking temperature and subjected to conversion while traveling in a stream of restricted cross-sectional area through a heating zone, introducing resulting cracked products inio said evaporating zone, removing liquid residue from said evaporating zone and introducing it into a flashing zone under reduced pressure wherein partial vaporization vof said residue occurs,` and passing vapors so obtained through said stripping zone in contact with said fresh relatively heavy charging stock while preventing thepassage of any unvaporized portions of said residue last-mentioned through either of said cracking zones.

6."I'he process of treating hydrocarbon oil4 which comprises separating from crude oil, without cracking, light gas oil and topped crude, introducing said topped crude into an intermediate point in an evaporating zone over contact surfaces therein to be heated by counter-current contact with hot vapors therein, whereby the said topped crude is subjected to partial vaporization i while passing in down-flowing streams against the upwardly-rising vapors, removing heated topped crude from an intermediate point in said zone lower than that first mentioned, cracking the removed topped crude by application of heat, introducing the hot cracked products into a low point in said zone to permit vaporization thereof, contacting with the resulting vapors at a point below and at a point above said intermediate points with a counter-current flow of relatively cool light gas oil derived from said crude oil to cause reuxing thereof, and removing gasoline containing vapors from the top of said zone.

7. The process of treating hydrocarbon oil which comprises passing gas oil and naphtha com-l prising essentially heavy fractions of gasoline in separate streams of restricted cross-sectional area through convection and radiant sections of a common heating zone and heating different portions of each of said streams preponderantly by convection heat and radiant heat respectively, to raise them to conversion temperatures and cause cracking of said gas oil and reformation of said naphtha, introducing the reformed naphtha directly into a vapor separating zone, additionally reacting the cracked gas oil in an enlarged unheated soaking zone, introducing the resulting soaked products into said separating zone and removing the separated vapors and fractionatin them to form al desired light distillate. Y

8. The process of treating hydrocarbon oil which comprises contacting crude oil with vapors from a residue flashing operation to cause vaporization of the lighter constituents thereof, condensing from the resulting vapors a heavy naphtha condensate comprising essentially heavy fractions of gasoline, removing unvaporized portions -of the crude oil and subjecting them to further vaporization by passing them downwardly through a first fractionating zone, over contact surfaces therein, in countercurrent contact withA rising highly heated vapors, whereby the liberated vapors quickly separate from a mixture of liquid residue and heavy condensate', removing the said mixture and raising it to a cracking temperature while passing through a heating zone in a stream of restricted cross-sectional area, introducing resulting cracked products into a vapor separating zone, passing vapors from said separating zone into said first fractionating zone as said highly heated vapors, removing liquid residue and ashing it under reduced pressure to form said vapors first mentioned, raising said heavy naphtha condensate to cracking temperatures under reforming conditions in an individual heating zone, introducing the resulting reformed products'into said separating zone, and removing fractionated vapors from said irst `:Eractionating zone and subjecting them to further fractionation to form a desired light distillate. f

9. A process for treating raw crude oil which comprises heating said oil, subjecting the heated oil to distillation to separate therefrom products including heavy naphtha comprising essentially heavy fractions of gasoline, subsequently heating the unvaporized portions of the reduced crude oil to a temperature suiicient to promote mild cracking, passing the heated oil into an evaporating zone, removing vapors from said evaporating zone, and passing them to a fractionating zone to produce a light overhead fraction and a condensate, cracking said condensate in the vapor phase, introducing the resulting heated vapors into said evaporating zone, heating said heavy naphtha to a, reforming temperature and introducing the heated naphtha into said evaporating rzone, re-

moving liquid residue from the bottom of saidA evaporating zone, subjecting it, while still hot, to a flashing operation to produce vapors and passing said vapors into contact with said crude oil prior to the heating thereof to the cracking temperature. l

10. The process 'of treating hydrocarbon oil which comprises introducing fresh relatively .heavy charging stock into a stripping zone wherein partial vaporization thereof occurs, removing the residual portion of said charging stock and introducing it into an upper level in an evaporating zone wherein hot vapors pass upwardly countercurrent to the residual portion so introduced, causing partial vaporization thereof, removing from an intermediate level in said evaporating zone below said upper level unvaporized portions of said residual portion in mixture with con-rl densed fractions of the rising vapors, passing the resulting mixture through a cracking zone wherein it is raised to a cracking temperature and subjected to conversion while traveling in a stream of restricted cross-sectional area through a heating zone, introducing the resulting cracked products into a still lower level in said evaporating zone, wherein vapors separate from liquid residue, fractionating vapors liberated in said evaporating zone to form a final desired light distillate and a rei-lux condensate, withdrawing liquid residue from said ,evaporating zone, reducing the pressure on the residue so Withdrawn to cause partial vaporization thereof, passing resulting vapors upwardly through said stripping zone to aid in the distillation of said fresh relatively heavy charging stock, arid blending with the unvaporized portions of said residue last-mentioned at least a portion of said reflux condensate to form fuel oil and isolating the fuel oil from the process,

, mediate level.

withdrawing clean reflux condensate` from said strippinguzone and passing it through a third zone wherein it is raised ,to a cracking` temperature and subjected to conversion, andfintroducing resulting hot products of conversion into said evaporating Zone at a point below said inter- 20 reux condensate to said cracking zone, removing liquid residue from said evaporating Zone and in' troducing it into a flash zone under reduced pressure wherein partial vaporization of said residue occurs, passing resultant vapors into a' stripping zone, introducing charging stock containing gasoline constituents into said stripping' Zone in contact with the vapors therein to effect partial vaporization thereof, removing the resultant residue portion' of said charging stock and introducing it into said evaporating zone to dephlegmate separated vapors therein and effect further vaporization thereof, fractionating vapors evolved in said stripping zone to form a distillate containing gasoline constituents, passing said distillate through a -reforming zone wherein it is raised to a cracking temperature sufficient to cause the reformation thereof and is converted into products of increased `anti-knock quality and directing the resultant products of the reforming into said evaporating zone.

PERCIVAL KEITH, JR. 20 

